1. Field of the Invention
The present invention relates to a method of producing a thermal-developable photosensitive material and, more particularly, to a method of producing a thermal-developable photosensitive material by simultaneously applying materials for a photosensitive layer, an intermediate layer and a protective layer to a surface of a substrate.
2. Description of the Related Art
In recent years, in the field of production of films for medical diagnosis and photoengraving films, there has been a strong demand for reductions in the amounts of waste processing solutions from the viewpoint of environmental protection and space saving. Therefore, techniques are required which relate to a thermal-developable photosensitive material formed as a film for medical diagnosis and a photoengraving film and capable of efficient exposure with a laser image setter or a laser imager and forming a clear black image having a high resolution and a high degree of sharpness. The thermal-developable photosensitive material has the advantages of requiring no processing chemical solution and enabling clients to be supplied with a thermal-developable processing system which is simpler and is designed to avoid any damage to the environment.
The thermal-developable photosensitive material is produced by simultaneously applying materials for a photosensitive layer, an intermediate layer and a protective layer to a surface of a flexible substrate (hereinafter referred to as xe2x80x9cwebxe2x80x9d). Ordinarily, the photosensitive layer contains styrene-butadiene rubber (SBR), behenic acid, an Ag dispersion and silver halide, and the protective layer contains phthalic acid. The material forming the intermediate layer is caused to flow between the photosensitive layer and the protective layer so as to prevent components of the photosensitive layer from contacting with components of the protective layer.
The conventional thermal-developable photosensitive material, however, has a problem that there is a possibility of the intermediate layer being broken by disturbance at the time of simultaneous multiple layer application of the photosensitive layer, the intermediate layer and the protective layer to allow SBR in the photosensitive layer and phthalic acid in the protective layer to contact with each other to cause coagulation. Coagulation in the photosensitive layer results in a defective coating surface condition seen as streaks or the like after application.
In view of the above-described circumstances, the present invention is achieved and an object thereof is to provide a method of producing a thermal-developable photosensitive material which prevents mixing of materials between layers to ensure that the coating surface is in a good condition.
To attain the above-described object, the present invention is directed to a method of producing a thermal-developable photosensitive material obtained by forming, on a substrate, a photosensitive layer, a protective layer for protecting a surface of the photosensitive layer, and an intermediate layer between the photosensitive layer and the protective layer, wherein a pH of a coating liquid forming the intermediate layer is set within a range from 5 to 10.
The present inventor experimentally obtained the knowledge that when a photosensitive layer, an intermediate layer and a protective layer are formed on a substrate by applying liquids for forming the layers to the substrate, the resulting coating surface condition varies by being influenced by the pH of the intermediate layer coating liquid. More specifically, a coating surface condition satisfactory as a property of a product can be obtained by adjusting the pH of the intermediate layer coating liquid to 5 to 10. According to the present invention, the pH of the intermediate layer coating liquid is adjusted to 5 to 10 to obtain a good coating surface condition.
Preferably, a salt for pH buffering is added to the coating liquid forming the intermediate layer. The pH of the intermediate layer coating liquid is therefore maintained in the range from 5 to 10 to achieve a more preferable coating surface condition.
To attain the above-described object, the present invention is also directed to a method of producing a thermal-developable photosensitive material obtained by forming, on a substrate, a photosensitive layer, a protective layer for protecting a surface of the photosensitive layer, and an intermediate layer between the photosensitive layer and the protective layer, wherein a viscosity of a coating liquid forming the intermediate layer is set within a range from 20 to 150 mPaxc2x7s.
The present inventor also experimentally obtained the knowledge that when a photosensitive layer, an intermediate layer and a protective layer are formed on a substrate by applying liquids for forming the layers to the substrate, the resulting coating surface condition varies by being influenced by the viscosity of the intermediate layer coating liquid. More specifically, a coating surface condition satisfactory as a property of a product can be obtained by adjusting the viscosity of the intermediate layer coating liquid to 20 to 150 mPaxc2x7s. According to the present invention, the viscosity of the intermediate layer coating liquid is adjusted to 20 to 150 mPaxc2x7s to obtain a good coating surface condition.
Preferably, the concentration of a binder in the intermediate layer coating liquid is set to 5 to 20%, thereby further improving the coating surface condition achieved. That is, if the binder concentration is lower than 5%, the coating surface condition deteriorates considerably. If the binder concentration is higher than 20%, the liquid cannot be fed. The binder concentration is set within the range from 5 to 20% to avoid such undesirable results with reliability.